From e0de0206a2a37cd3e0ba9954d9f863e11d6d1782 Mon Sep 17 00:00:00 2001 From: Jens Axboe <axboe@suse.de> Date: Thu, 1 Jun 2006 10:07:26 +0200 Subject: [PATCH] [PATCH] cfq-iosched: check busy queues before deciding we are idle For just one busy queue (like async write out), we often overlooked that we could queue more io and decided we were idle instead. This causes us quite a bit of performance loss. Signed-off-by: Jens Axboe <axboe@suse.de> --- block/cfq-iosched.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 11ce6aaf1bd02..d582433441c50 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -878,6 +878,13 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) if (!list_empty(&cfqd->cur_rr) || cfq_get_next_prio_level(cfqd) != -1) cfqq = list_entry_cfqq(cfqd->cur_rr.next); + /* + * If no new queues are available, check if the busy list has some + * before falling back to idle io. + */ + if (!cfqq && !list_empty(&cfqd->busy_rr)) + cfqq = list_entry_cfqq(cfqd->busy_rr.next); + /* * if we have idle queues and no rt or be queues had pending * requests, either allow immediate service if the grace period -- GitLab